Toronto • May 28-29, 2010 • Student Day and Workshops: May 27
Program > Saturday > 11:15 > Session symposium. Symposium: Carcinogens in the Ontario Workplace: Work of the new OCRC
Paper: Radiation and cancer: Long-term risks in Ontario uranium miners
Author(s) and Affiliation(s):
Minh T. Do, Centre for Research in Environmental Epidemiology (CREAL); Cancer Care Ontario
Loraine D. Marrett, Occupational Cancer Research Centre
James Purdham, Dalla Lana School of Public Health and Gage Occupational and Environmental Health Unit, University of Toronto
Wendy Lou, Dalla Lana School of Public Health, University of Toronto
Jennifer I. Payne, Department of Diagnostic Radiology, Dalhousie University
Day/Time: Saturday at 11:15
Room: Giovanni Room, 2nd Floor
Objectives:
Excess lung cancer risk associated with exposure to inhaled radon decay products among uranium miners is well established. Although ingestion is also a potentially important route of exposure, risk associated with non-lung cancer sites has not been well examined. The objective of this presentation is to examine the relationship between exposure to radon decay products and the incidence and mortality of cancers other than lung among the Ontario cohort of uranium miners.
Methods:
A cohort of miners who had ever worked in an Ontario uranium mine between 1954 and 1996 was created using the Work History File and the National Dose Registry. Cumulative radon exposures measured in Working Level Months (WLM) were estimated by year and mine for each miner. Cancer diagnoses (1964-2004) and cancer deaths (1954-2004) occurring in Ontario were determined by probabilistic record linkage with the Ontario Cancer Registry. Non-cancer deaths were also ascertained from the Ontario mortality file, 1954-2004, to calculate person years at risk. Poisson regression methods for grouped data were used to estimate the relative risks (RR) and 95% confidence intervals (CI) by exposure level.
Results:
The final cohort consisted of 28,273 Ontario uranium miners. By the end of 2004, 2926 miners had been diagnosed with cancer and 1640 died from cancer (all sites). Excesses in lung cancer mortality were confirmed. When comparing the highest cumulative exposure category (>40 WLM) to the referent group (0 WLM), significant increases in both stomach (RRIncidence= 2.30, 95% CI =1.02-5.17 and RRMortality=2.90, 95% CI=1.11-7.63) and colorectal cancers (RRIncidence =1.56, 95% CI=1.07-2.27 and RRMortality =1.74, 95% CI=1.01-2.99) after adjusting for age at risk and period effects. No excess risks were observed for other cancer sites including brain, bladder, and kidney.
Conclusions:
In addition to lung cancer risk, analyses from this study suggest that occupational exposure to radon decay products among Ontario uranium miners increases the risk of diagnosis and death from stomach and colorectal cancers.
